Great theories stand the test of time—shedding light on their subject’s essence despite varying contexts, technological upheavals or mutable human relations. One such work is Carl von Clausewitz’s On War. That said, with the detonation of the atomic bomb and the proliferation of nuclear weapons, many find Clausewitz wanting. How can there be a decisive battle without nuclear annihilation? Nuclear weapons seem to breach our understanding of force, suggesting the need for radically different conceptions of war. Enter Thomas C. Schelling and his work on The Strategy of Conflict—an attempt to comprehend and harness force within the context of nuclear weapons. Surprisingly, both Schelling’s and Clausewitz’s projects are far more similar than their diverging contexts would suggest. Lest we forget, the transformations in war that they bore witness to—Napoleon and nukes—were similarly jarring; despite the difference in potency, the rupture in the traditional form of war corresponds. After the introduction of these methodological and technological terrors, Clausewitz and Schelling spent their time trying to comprehend what these changes meant for war and conflict—in theory and in reality—converging on the problem of delimiting war. While Clausewitz’s problem is limited war and Schelling’s problem is limiting warfare, both turn to the concept of the threat to compensate for the failure of war in reality to realize its theoretical potential. Ultimately the difference between Clausewitz and Schelling lies in the utility of threat.

War can never be perfect in the absolute sense. In On War, Clausewitz begins with the axiom that “war therefore is an act of violence intended to compel our opponent to fulfill our will.”[1] He then deduces that in war we should employ the utmost use of force to make our opponent defenseless. Ideally, we employ all our military might in a forceful singularity that necessarily disarms the enemy. As a result, we would not worry about nor even contemplate our opponent’s actions. Rather than a dialogue of forces, there would only be an instantaneous soliloquy expressing war absolutely. Nevertheless, when Clausewitz looks to reality and consults the historical record, he finds that this is anything but the case. Singularity is not possible.[2] War takes time in space giving the opponent a stake in the outcome. Clausewitz makes this clear, writing, “As long as the enemy is not defeated, he may defeat me…he will dictate the law to me as I did to him.”[3] In reality war is interactive; this fact limits war. We have to plan and account for the opponent; if we push, the opponent pushes back. Clausewitz argues, “The Art of War has to deal with living and with moral forces, the consequence of which is that it can never attain the absolute.”[4] Each side is composed of fallible, fickle, and frustrating humans. Just as we are acting and reacting, so too is the enemy. And, as long as there is an enemy then war is not, and never will be, absolute.

War will never be perfect in the absolute sense and neither can it be perfect in the purest sense.[5] In The Strategy of Conflict, Schelling explains that pure conflict is the naturally untenable case of a zero-sum game.[6] An instance of pure conflict—a zero-sum game—is when what is gained for one side is exactly what is lost for the other. Pure conflict emerges when “the interests of two antagonists are completely opposed.”[7] It results when certain variables are held constant, specifically (and similar to Clausewitz) interaction and interdependence with the opponent. Fortunately, pure conflict “is a special case; it would arise in a war of complete extermination, otherwise not even in war.”[8] Instead, “most conflict situations are essentially bargaining situations” in which interaction and interdependence with the opponent is fundamental, a concept that pure conflict eschews.[9] Schelling continues, “The ability of one participant to gain his ends is dependent to an important degree on the choices or decisions that the other participant will make.”[10] Like Clausewitz, Schelling understands the limit toward reaching the purest conception of conflict. Warfare is limited because each choice is dependent on expectations ad infinitum: “Everyone expects everyone else to expect everyone else to expect the result.”[11] If we are expecting something and our opponents are similarly expecting, neither is fully acting. Each relies on the other whose humanity makes war imperfect.[12]

According to Schelling, coordination is the process that stabilizes conflict enabling limited warfare while politics functions comparatively for Clausewitz. Schelling worries, “There is no stable focal point except at the extremes.”[13] At the extremes, conflict is a dichotomy of tit-for-tat. With the introduction of coordination—a byproduct of interdependence with the enemy—there is the possibility for stability and limited warfare. It is a precarious balance held in place by cooperation and threats. Likewise, Clausewitz justifies, “If the whole consideration is a calculation of probability based on definite persons and relations, then the political object, being the original motive, must be an essential factor in the product.”[14] Within a limited war, politics reemerges manipulating people and their relations within the scope of the war. Clausewitz’s war cannot express itself as a singularity of force coextensive with the desired political object; instead, politics maintains a leash on war controlling its expression. It is not a question as to whether politics or coordination makes war imperfect, but instead how politics and coordination delimit it. Since war is neither pure nor absolute, coordination and politics are used to bridge the gap that necessarily results when theoretical war is not coextensive with war in reality. It is in this space—between theoretical war and war in reality—wherein politics and coordination maneuver. They become methods that not only compensate for, but also attempt to exploit, the necessary existence of the opponent and their say. Clausewitz and Schelling appeal to the concept of the threat to enable politics and coordination the requisite level of control.

Schelling defines threats as “no more than a communication of one’s own incentives, designed to impress on the other the automatic consequences of his act.”[15] Unpacking this we find that threats are expressive of potentiality of a possible scenario deriving from a future action. Schelling explains that the goal is to “[influence] the other person’s choice, in a manner favorable to one’s self, by affecting the other person’s expectations on how one’s self will behave.”[16] We communicate to our opponent—be it through language or action—that if a certain something happens, then we will react in such a way.[17] This oppositional interdependence is crucial because only when the linkage is active can threats take effect necessarily limiting warfare. Moreover, it is essential that “one must threaten that he will act, not that he may act, if the threat fails.”[18] The threat must resonate with the opponent because “the threat’s efficacy depends on the credulity of the other party, and the threat is ineffectual unless the threatener can rearrange or display his own incentives so as to demonstrate that he would, ex post, have an incentive to carry it out.”[19] Threats only work if our opponent imagines the same (or at least a similar enough) future state based on the threat’s potentiality, would prefer that the future not turn out that way, and believes we will carry out the action invoked by the threat. The difficulty in threatening is convincing the enemy without demonstration. Therefore, Schelling’s threats rest heavily on communication and the coordination that it facilitates, Clausewitz, on the other hand, differs.

While Schelling is far more formal in his explanation of threats, Clausewitz notes their purpose. Clausewitz’s concept emerges when “this influence of the political object is once permitted, as it then must be, there is no longer any limit, and we must be pleased to come down to such warfare as consists in a mere threatening of the enemy and in negotiating.”[20] Here is the clearest expression of limited war begetting threats, but it is unclear what Clausewitz means by “mere threatening.” We must first remember “All action, therefore, takes place on the supposition that if the solution by force of arms which lies at [War’s] foundation should be realized, it will be a favorable one.”[21] How is it possible to reconcile the need for a forceful decision and the political possibility of threats? Clausewitz explains, “If, therefore, the enemy is to be reduced to submission by an act of War, he must either be positively disarmed or placed in such a position that he is threatened with it.”[22] This might seem circular, but we are closer to the understanding Clausewitz’s conception. A threat is the possibility of future military action based on the disposition of the forces at that time. Disarmament of the enemy is still essential to his conception of war, but he allows for human expectation of the probability of certain results based on the disposition of the world, precisely the configuration of military forces. This is conceivable because it is still based on disarmament specifically through “possible combats.”[23] The projection of the “supposition of force” constitutes the threat; threats are “demonstrations.”[24] Just like Schelling, Clausewitz relies on expecting the opponent to think in a certain way about the future and his (possible and probable) future actions. Additionally, the opponent must be receptive to threat. Unlike Schelling, credibility—belief in the actual execution of the action implied in the threat—is based on communication of the inevitable force of combat constructed from the multiplicity of forces in space and time, rather than through language and dialogue.[25] Invoking the fear of the direct clash of force—creating the perception of the inevitability of overwhelming military force—is the Clausewitzian threat.

A CLAUSEWITZIAN THREAT SEEMS LESS LIKE A THREAT, COMMONLY DEFINED, AND MORE LIKE AN INDICATION OF INTENT, A SPECTER OF FUTURE DECISIVE FORCE.

Clausewitz and Schelling diverge on the utility of threats because of their shortcomings and potential for misapprehension. A threat from Clausewitz’s perspective is merely more expedient and cost-effective, but executing the threat should always remain viable and even desired. A Clausewitzian threat seems less like a threat, commonly defined, and more like an indication of intent, a specter of future decisive force. Whereas, Schelling’s threats are actions of a different sort, a coordinated bargaining dance. This difference is most apparent when we consider Schelling’s “threat that leaves something to chance.” Schelling explains, “The key to these threats is that, though one may or may not carry them out if the threatened party fails to comply, the final decision is not altogether under the threatener’s control.”[26] Although Clausewitz accommodates chance within his trinity, threatening without the underscored notion of forceful decision is inherently wrong. Furthermore, Clausewitz would trivialize this threat, because “all action in War…is directed on probable, not on certain, results. Whatever is wanting in certainty must always be left to fate, or chance, call it which you will.”[27] To Clausewitz the threat that leaves something to chance is a tautology. Rather, Clausewitz’s main concern is that our enemy would not respect the limitations and would instead take advantage of the delay—inherent in the nature of a threat—to use force to disarm us. There is always the risk that the enemy will use the trump card of immediate and decisive force. The irony is that fear of escalation is what Schelling believes will build stability in an oppositional relationship advocating “Deliberately raising the risk of all-out war is thus a tactic that fits the context of limited war.”[28] The potential for war to spin out of control—in spite of its limitations—and approach its pure and absolute formulation constitutes Schelling’s threat, and, moreover, this possibility in itself preserves stability just because neither side desires the outcome. Instead, Clausewitz fears the possibility that our opponent will take advantage of limited war and make it not as limited to the extent that we will instead be destroyed. If we consider Clausewitz and Schelling enemies threatening one another, then Schelling would threaten the risk of less limited war, à la nukes, while Clausewitz would respond not with threats, but with force.[29]

In the end, since war in reality is neither pure nor absolute, both Clausewitz and Schelling empower politics and coordination to employ threats to exploit the necessary essential limitations on war. Schelling’s threats are the credible communication of our future actions based on our opponent’s actions. Clausewitz’s threats are based on the configuration of military forces with the implicit expectation of future combat—his definition of strategy.[30] Schelling too finds the strategy of conflict “is the employment of threats, or of threats and promises.”[31] However, the difference lies in the utility of the threat. While Schelling finds the threat to be the beacon of stability and the possibility to limit warfare, Clausewitz is pragmatic and understands that ultimately realistic and executable force must underpin all threats. Schelling would prefer never to have to carry out a threat. A nuclear Clausewitz would have no compunction in their execution provided the requisite political thrust. Whereas, Schelling believes that threats are necessary and sufficient to engage with the enemy, Clausewitz finds threats often necessary, but certainly insufficient without real force and its specter in support.

Olivia A. Garardis an officer in the U.S. Marine Corps, a Featured Contributor to The Strategy Bridge, and an associate member of the Military Writers Guild. The opinions expressed are hers alone and do not reflect those of the U.S. Marine Corps, the Department of Defense, or the U.S. Government.

NOTES:

[1] Carl von Clausewitz, On War, trans. Colonel J. J. Graham (New York: Barnes & Noble, Inc., 2004): 3. [Italics original]. I use Graham’s translation over the Paret/Howard version because their translation is predisposed to a nuclear context. Consider their translation of “policy” over “politics” in many instances as a deliberate attempt to further limit war by limiting the theory behind it.

[2] While a Clausewitzian singularity might seem eerily foreboding of the atomic bomb, Schelling and his “second strike capabilities” argument demonstrates that this absolute expression of force is still not possible. The nukes we have are not nuclear enough.

[3] Clausewitz, 6.

[4] Ibid., 17.

[5] Much of Schelling’s work is directed at conflict, broadly defined, rather than only war. This is fine since conflict is inclusive of war. All wars are conflicts, but not all conflicts are wars.

[12] This does have potential consequences for autonomous robots in war as Peter W. Singer’s Wired For War suggests. Perhaps programming is sufficient to consider a human in the loop?

[13] Ibid.

[14] Clausewitz, 10.

[15] Schelling, 35.

[16] Ibid., 160.

[17] While there is difference between “a threat intended to make an adversary do something (or cease doing something) and a threat intended to keep him from starting something,” only a threat broadly defined is necessary. [Ibid., 195].

[18] Ibid., 187. [Italics original].

[19] Schelling, 36. [Italics original]

[20] Clausewitz, 698. [Italics original] It is interesting that Clausewitz considers them mutually exclusive, whereas, Schelling would consider them two-sides of the same coin of diplomacy.

[21] Ibid., 32.

[22] Ibid., 6.

[23] Clausewitz, 547. [Italics original]

[24] It is a shame On War is incomplete because we do not have the chapter alluded to on “Demonstrations.” Or even the likely Book VIII Chapter 10, “Plan of War When the Destruction of the Enemy is Not the Object.” [Ibid., 520].

[25] Schelling would permit Clausewitz’s “tacit communication” but not vice versa, unless Schelling’s dialogues were backed up with (impending) force. Note Schelling: “[moves] have an information content, or evidence content” but “of a different character from that of speech” [Schelling 117.]

[26] Ibid., 188.

[27] Clausewitz, 119.

[28] Schelling, 193.

[29] But what happens after that?

[30] Specifically, “Strategy is the theory of the use of combats for the object of the War” [Clausewitz, 71].